Question: 1. A rod of length 3 meters with density δ(x) = 1+ x2 grams/meter is positioned along the positive x-axis, with its left end at the origin. Find the total mass and the center of mass of the rod.
2. One half of a uniform circular disk of radius 1 meter lies in the xy-plane with its diameter along the y-axis, its center at the origin, and x > 0. The mass of the half-disk is 3 kg. Find (x¯, y¯).